Pine-gum rosin ddt insecticide compositions



Patented Oct. 30, 1951 PIN Ill-GUM ROSIN DDT INSECTICIDE COMPOSITIONS W. T. Sumerford and Jens A. Jensen, Atlanta, Ga., assignors to the United States of America as represented by the administrator, Federal Security Agency No Drawing. Application June 30, 1949, Serial No. 102,441

1 Claim. (Cl. 167-30) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Government of the United States for governmental purposes without the payment to us of any royalty thereon in accordance with the provisions of the act of April 30, 1928 (Ch. 460, 45 Stat. L. 467).

This invention relate to insecticidal compositions and to processes for their use. More specifically, this invention relates to means for prolonging the toxicity of persistent contact insecticides such as DDT, chlordane (chlorinated hydrocarbon derivatives), and Toxaphene (chlorinated camphene) Heretofore, flies, mosquitoes, and the like have been controlled by spraying, dusting, or otherwise applying DDT or the like to surfaces upon which the insects are likely to alight. The chemical now commonly called DDT and which will be so referred to hereinafter, is the insecticide described in U. S. Reissue Patent No. 22,922 issued in the name of Paul Muller, and can be designated 1,1,1-trichloro-2-bis- (p-chlorophenyl) ethane. DDT owes its efficacy to the fact that it is toxic to a wide variety of insects with which it may be brought into contact, and at the same time it is relatively persistent in its action, compared with nicotine or the like. However, it is quickly inactivated on surfaces exposed to the full action of the weather, especially in areas having a high rainfall. The loss in toxicity of DDT within the matter of week has never been fully explained, but it has now been discovered that an inexpensive, readily available material can be incorporated in DDT concentrates whereby panels coated therewith remain toxic to house flies or the like for as long as five months exposure to direct sunlight and eighteen inches of rainfall.

This invention has for an object the provision of an insecticidal concentrate capable after dilution of treating surface so they will remain toxicto insects after many months exposure to severe weathering. Another object is the provision of an insecticidal concentrate containing DDT and an additional agent, which can be diluted with water and applied through ordinary spraying devices. Another object is to provide a process for rendering exterior surfaces exposed to the weather toxic to insects for a prolonged period of time merely by treating such surfaces with an aqueous dispersion of DDT containing substantial proportions of an addition agent effective in promoting the weather resistance of the thus-applied DDT. Other objects will be apparent or will appear hereinafter as the ensuing description proceeds.

These objects are accomplished in accordance with this invention which provides an insecticidal concentrate comprising a xylene solution of DDT and rosin capable of dilution with water to form an aqueous emulsion which when applied to surfaces and dried remains highly toxic and resistant to weathering. An important feature of this invention is the relationship of the quantity of DDT to the quantity of rosin (by which is meant pine-gum rosin).

In order to secure the prolonged weather resistance made possible by this invention, there should be employed between 25% and 50% by weight of pine-gum rosin, based on DDT content. Thus, a concentrate containing 25% by weight of DDT would contain between 6.25 percent and 12.5 percent by weight of pine-gum rosin, based on the entire weight of the concentrate, but would contain between 25% and 50% by weight of pine-gum rosin based on DDT content of the concentrate. To our knowledge, no one has heretofore considered utility to reside in the employment of such large quantities of pine-gum rosin in an insecticidal composition.

While this invention is not to be limited by any theoretical explanation concerning its operation, nevertheless, based on information presently at hand, it is thought that by dissolving the rosin and the DDT in a mutual solvent therefor, such as xylene or the like, and thereafter emulsifying this solution in water, there results an intimate co-mingling of rosin with DDT such that the combination behaves upon application like rosin while carrying the toxic properties of DDT. It is not beyond the realm of possibility that a solution of DDT in a rosin film may result in accordance with this invention after the evaporation of water and toluene from the applied emulsion. The following example illustrates the preparation of a 25% DDT concentrate containing 40% by weight of rosin, based on DDT content:

Example 1.36 gallons of xylene are mixed with lbs. of DDT and agitated in a power mixer until the DDT is completely dissolved. 42 lbs of pine-gum rosin are broken into small lumps not greater than inch in diameter and the broken rosin is then dissolved in the DDT solution. There results about 50 gallons of solution containing 25% DDT, based on total solution, and 40% rosin, based on DDT content.

Before spraying, the above prepared concentrate is mixed with water in the proportion of one gallon of water to one quart of 25% concentrate. The resulting aqueous emulsion was sprayed on glass panels and compared with pan- Weeks of Exposure;

Formulation 2 V 4 6 8 Percent Kill of Flies stiajnlglard 5% emulsion, 200 mg./sq. it.

Standard 5% emulsion rosin, 200

mg./sq. ft. DDT Rainfall in inches It will be noted from the tabulated percent killed of flies that at the end of eight weeks the rosin formulation still killed 100% of the flies while in the absence of rosin, the percent kill had dropped to only 8%. After further exposure for a period of five months to direct sunlight and eighteen inches of rainfall, the treated glass panels continued to show satisfactory house fly control.

Example 2.Example 1 was repeated incorporating one gallon of an emulsifier known as Triton X-100 in the concentrate. Upon dilution with water, the emulsion was stabilized without requiring agitation.

From the foregoing, it will be seen that there has been provided by this invention a cheap, effective, insecticidal concentrate capable of rendering treated surfaces toxic to insects such as house flies or the like for prolonged periods of time even when exposed to direct weathering. In general, it has been found that xylene forms a very satisfactory mutual solvent for DDT and pine-gum rosin although other mutual solvents are not excluded, such as, for example, ethyl alcohol, turpentine, kerosene, or the like. It is preferred to employ between 25% and 50% by weight of pine-gum rosin based on DDT content. For many purposes, these proportions are probably critical inasmuch as substantially larger proportions of rosin do not permit free spraying in aqueous emulsion, while amounts of pine-gum rosin substantially smaller than 25% by weight, based on DDT content, fail to provide the great resistance to weathering.

While the examples disclose the treatment of glass test panels, it has been found in use that exterior surfaces exposed to weather such as wood, vegetation, fence rails, barns, and other outbuildings, can be treated in accordance with this invention to give complete control of house files or the like for an entire season with one application.

While we prefer to employ DDT itself, similar results may be achieved using chlordane, toxaphene, and other persistent organic contact insecticides.

Although it is preferred to employ the concentrate in the form of an aqueous dispersion or emulsion, it is within the contemplation of this invention to employ instead a mutual solvent in larger proportions such as, for example, employing toluene or the like so as to yield a final spray solution containing about 3 to 5% DDT and 1.75 to 2.5% pine-gum rosin. In general, however, the most economical application is made in aqueous dispersion. It should be noted that the efiicacy of this invention does not require the presence of a dispersing agent or emulsifier, but in order to stabilize the aqueous emulsions of this invention, it is desirable to incorporate a suitable dispersing agent of the type known to those skilled in the art. For example, sodium dodecyl sulfate, the ammonium salt of lauryl ethylene glycol sulfate, and mannitan monolaurate may be used as emulsifying or dispersing agents.

Various changes can be made in the invention as above described in its preferred embodiments without departing from the spirit and scope thereof.

What is claimed is:

An insecticidal concentrate consisting essentially of a xylene solution of DDT and between 25 and percent of pine-gum rosin, based on DDT content.

W. T. SUMERFO-RD. JENS A. JENSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,412,720 Dolman Dec. 1'7, 1946 2,414,216 Wean Jan. 14, 1947 2,462,835 Arnold Mar. 1, 1949 OTHER REFERENCES Langford in J. Econ. Entomology, vol. 38, April 1945, pp. 202-204.

Block in Soap & Sanitary Chemicals, February 1948, pp. 138-141 and 171. 

